Oops - wrong short circuit test - just realized. Sorry about that. My mind is occupied by that one currently...
The on-board short-circuit test is to simulate a short occurring for whatever reason (manufacturing defect, design defect, operational fault). Since something bad happened, in my opinion the card is allowed to fail as long as it fails safe. Opening a fuse is certainly an acceptable method to remove the electrical safety hazard. ...Marko -----Original Message----- From: Marko Radojicic Sent: Monday, November 25, 2002 11:14 AM To: 'j...@aol.com'; emc-p...@majordomo.ieee.org; t...@world.std.com Subject: RE: Short circuit tests in GR-1089 Joe, The short-circuit test is to simulate the most prevalent source of telecom disruption: the back-hoe. When a buried cable is inadvertently cut, the pairs could short together or to the cable sheath. I really can't see how a test lab can misinterpret the requirement (R4-6 for telecom ports). It clearly states that replacing fuses is not an allowable situation. "The EUT shall not be damaged, shall not require manual intervention (such as to reset circuit breaker or replace fuses) to restore service, and shall not become a fire, fragmentation, or electrical safety hazard as a result of the application of a short circuit ..." I'm quite sure that whomever you spoke with at the test lab is in error and will probably reconsider their position if they read the standard a little more carefully. Cheers, Marko Marko Radojicic Manager, Compliance and Reliability Turnstone Networks, inc. 2220 Central Expressway Santa Clara, CA 95050 mar...@turnstone.com 408/907-1739 -----Original Message----- From: j...@aol.com [mailto:j...@aol.com] Sent: Monday, November 25, 2002 10:25 AM To: emc-p...@majordomo.ieee.org; t...@world.std.com Subject: Short circuit tests in GR-1089 Hello All: I am hoping that some of you can help clarify the intent of requirement R9-20 in Telcordia GR-1089. Taken literally, the requirement says that there shall be no damage to equipment, conductors, or components when the DC power supply is shorted at the load. This could even be interpreted to preclude the use of a fuse that has to be replaced. One test lab has told me that as long as no fire hazard is created from this test, it is considered to have been passed. Needless to say, this differs a bit from the literal interpretation. I guess it would help if I had a better feel for the overall goal of the short circuit testing. Any insight on this would be most appreciated. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
